Synthetic Fibres Class 8 Notes
In class 7 we read about Natural Fibres in the chapter Fibre to Fabric where we got the basic knowledge of Fibre and Fabrics.
The clothes that we wear are made up of fabrics and fabrics are made up of fibres which are obtained from either natural or synthetic fibres. In class 8 we will study Synthetic Fibres and Plastics.
Let us look at the best Synthetic Fibres Class 8 notes.
The main Topics of this Chapter are:-
- Monomers and Polymers
- Synthetic Fibres and types of Synthetic Fibres
- Plastics and types of Plastics
- Properties of Thermoplastic
- Properties of Thermosetting
- Advantages and Disadvantages of Plastics
Monomers and Polymers
What are monomers and Polymers?
Monomers are single-chain molecules that join together to form a large single unit called Polymer.
Polymer comes from two Greek words; poly meaning many and mer meaning part/unit. So, Polymer can be defined as many repeating units.
Examples: Cellulose is a natural polymer of Glucose units (monomer).
What is Polymerization?
The process of converting monomers into polymers is called polymerization.
What are synthetic fibres?
Synthetic Fibres are fibres (thin threads from which clothes are made) that are prepared by human beings through a number of processes using raw materials of petroleum origin, called petrochemicals.
Types of Synthetic Fibres
The types of synthetic Fibres that we are going to study in this chapter are as follows-
Rayon is a synthetic fibre that resembles the properties of Silk. It is called Artificial Silk.
- Rayon is obtained from wood pulp by chemically treating it.
- It is cheaper than silk and can be dyed in many colours.
Uses of Rayon
- Mixed with cotton to make bedsheets
- Mixed with wool to make carpets
It is the first fully synthetic fibre, developed in the year 1931. It was prepared from coal, water, and air.
Properties of Nylon
Some of the properties of Nylon are-
- very strong
- easily washable
Uses of Nylon
Nylon is used for many articles such as ropes, socks, tents, toothbrushes, car seat belts, sleeping, bags, curtains, parachutes, rock climbing ropes, etc.
Polyester is made from monomers called ester. Fabrics made from Polyester are not easily wrinkled.
Polyester is often mixed with other fibres (natural or synthetic) to enhance its properties.
Properties of Polyester
Here is a list of a few important properties of Polyester
- crease resistant
- good tensile strength
- easy to wash and wear
- water resistant and easily dries
Uses of Polyester
- suits, jackets, shirts, trousers etc.
- PET (a form of polyester) is used for making bottles, utensils, etc.
- water hoses for firefighting and conveyor belts
What does PET stand for?
PET is a short form of Polyethylene terephthalate. PET is a form of polyester used in the manufacturing of bottles, wires, utensils, etc.
Some common properties of PET are- strong and lightweight, transparent, recyclable, etc.
What are Blended Fibres?
These types of fibres are made by mixing two types of fibres.
For example- Polycot – is a mixture of Polyester and Cotton. Similarly, Polywool is a mixture of Polyester and Wool.
These are the synthetic fibres often used to make winter clothes like sweaters, shawls, etc. Acrylic is made up of Acrylonitrile polymer.
Properties of Acrylic
- It resembles wool
- good tensile strength
- Relatively cheaper than natural wool
- wrinkle resistant
- resistant to moths
- elastic and light in weight
Uses of Acrylic
- It is used to make shawls, sweaters, and blankets
- as furnishing fabrics and carpets
- used to make hair wigs
- used for making dresses of toys/dolls
Characteristics of Synthetic Fibres
Let us talk about some of the important characteristics of Synthetic Fibres.
Absorbs Less Water– Compared to natural fibres, synthetic fibres absorbs less water.
Durability– Synthetic fibres are more durable than natural fibres.
Cost– The price of synthetic fibres is not so high, easily available at cheaper rates.
Strength– compared to natural fibres, synthetic fibres has high tensile strength.
Resistivity– Synthetic Fibres are resistant to insects and moths.
Colours– Synthetic fibres are prepared using chemicals so available in a variety of colours.
Advantages and Disadvantages of Synthetic Fibres
|Fibres are stretchable
|Not easily absorbs sweat
|High load-carrying capacity
|Can catch fire easily
|Not comfortable to wear in a hot and humid climate
|A variety of colours are available
|Cheaper Synthetic Fibres can cause skin irritation
What are Plastics?
Plastics are polymers obtained by arranging monomers in straight chains or cross-linked chains. Plastic is derived from the greek word Plastikos and the Latin word Plasticus, meaning ‘it can be moulded into different forms or capable of moulding’.
Properties of Plastics
Some of the properties of plastics are-
- Cost Effective
- Poor Conductor of Heat
- Poor Conductors of Electricity
Types of Plastics
Plastics can be broadly categorized into two groups. These types of plastics are grouped on the basis of the arrangement of the monomers, or how the monomers are linked to each other. The two types of Plastics are as follows-
- Thermosetting Plastics
The arrangement of the smallest units, i.e, the monomers is in a straight line. These types of plastics can be easily reshaped or moulded on heating.
Examples– Polythene, PET, PVC
Properties of Thermoplastic
- easily remoulded to any shape
- becomes soft on heating
In the thermosets, the arrangement of the monomers is branched and cross-linked. These types of plastics cannot be easily reshaped or moulded on heating.
Examples- Bakelite and Melamine
Properties of Thermosetting
- cannot be remoulded
- cannot be softened on heating
Important Plastic Properties and Uses
Here is a list of some important plastics and their properties and uses.
It is a combination of two words- Poly and Ethene. It is obtained by polymerizing ethene. It is a type of thermoplastic type of plastics.
Properties and Uses of Polythene
Some of the properties of Polythene are- tough and durable
Uses of Polythene- making polythene bags, bottles, packets, waterproof plastic sheets, etc.
PVC (Polyvinyl Chloride)
It is also a type of thermoplastic. Monomer of PVC is Vinyl Chloride.
Properties and Uses of PVC
Properties of PVC are- It is hard and strong but not as flexible as Polyhthene.
Some uses of PVC are- it is used in the manufacturing of pipes, insulations, raincoats, etc.
Bakelite is a thermosetting type of plastic. The monomer of Bakelite is made up of phenol and formaldehyde.
Properties and Uses of Bakelite
Properties of Bakelite: It is hard, tough and poor conductor of heat and electricity.
Uses of Bakelite: Used for making handles of utensils, electrical switches, plugs, etc.
Melamine is another type of thermosetting plastic. It is a fire resistant plastic.
Properties and Uses of Melamine
Properties of Melamine: It is also hard, very durable, and versatile in nature.
Uses of Melamine: It is used for making tiles, cups, plates, and other unbreakable kitchenwares. It is used as coating for fire-men uniforms as it is fire resistant.
It is a type of synthetic polymer which contains carbon and fluorine. The monomer of teflon is tetrafluroethylene.
Properties and Uses of Teflon
Properties of Teflon: It is oil and water resistant due to its slippery surface. It can also withstand high temperature.
Uses of Teflon: It is used as coating in utensils to give a non-stick surface. Also used in electric irons, etc.
Uses of Plastics
There are many uses for plastics in our day-to-day life. We are highly dependent on the use of plastics. Here is the list of different uses of Plastics-
- Packaging Food items
- Every article we use is made up of plastics
- used for making mugs, buckets
- As an insulator
- Pipes and water tanks, etc.
Bad Effect of Plastic on the Environment
Plastics have made humans’ life easy in many aspects but at the cost of the environment. Plastics have a bad effect on the environment.
Here is a list of the bad effects of plastic on the environment.
- It is non-biodegradable so pollutes soil and the environment.
- Blockage of drains and sewers
- Burning of plastics produces harmful gases
- Kills animals
Steps to Save the Environment from Plastic Waste
We can take several steps to save the environment from the misuse of plastics.
List of Steps to save the environment from Plastics
- Minimum Use of Plastics
- Do not burn the plastics
- Proper disposal of plastics
- Use cloth bags instead of plastic bags
- Avoid single use plastics like plates, straws, etc
We can follow the 5 R Principle to save the environment.
5 R Principles
- Refuse– Refuse everything that is made up of plastics.
- Reduce- Minimize the use of plastics.
- Reuse- Learn to use it again and again before buying a new one.
- Repurpose- If you are not in need, then change or use it in a different way.
- Recycle- Plastics can be recycled in recycling factories.
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Hope you liked these CBSE Synthetic Fibres Class 8 Notes.